Probe has its own hit stun on airborne opponents, as does MB Probe. This (usually) makes it easier to extend your combo.
You can prove this by throwing out a Probe, delay a second and using B3. As the opponent is bouncing back from B3 the Probe should hit, stopping them dead in their tracks with a tiny pop up. Obviously this specific situation is bad for Lex, but it's to show what Probe does now. Before the patch the opponent would continue bouncing back to Lex even with the Probe hitting.
MB Probe has 2 'pop up' effects, with the second hit juggling them a bit higher. So far I've found it useful, converting some situations into combo with 11, or Corp Charge hard knockdown.
Before patch, the stagger animation on a Grounded opponent would usually make 11 whiff at distances it shouldn't .. I haven't tested extensively, but this doesn't seem to be the case anymore. Not sure if its a property of his improved normals or something to do with the Probe itself.
Name v.5.0 My experiences of the Probe changes so far.